In the medical field it is becoming more and more common practice to use stereo microscopes or cameras for assisting medical professionals in performing such tasks as medical surgeries, examinations, treatments and the like. Typically these optical devices provide for the possibility of zooming into a picture by means of a so-called pancreatic lens system. During zooming, some lenses of the pancreatic lens system are moved and must be brought into certain positions in relation to other fixed lenses with extraordinary precision in order to provide for a good image. Conventionally an annular cam disk milled with great care has been used to control the position of these lenses and thereby the overall quality of the optical device. A drawback of these conventional configurations is that the annular cam disk completely surrounds the optical system and the lenses thereof so that these elements are not readily accessible. Furthermore, the conventional systems leave virtually no space for installing additional components, such as control, drive and power supply units, resulting in rather bulky optical devices.
The object of the present invention is to provide for a zoom system for an optical stereo device overcoming or at least mitigating the problems associated with the above described conventional zoom systems.